Snow conditions 12. 3. 2025

General avalanche danger level - Wednesday, 12. 3. 2025
Danger level 3 on the European 5-level scale - CONSIDERABLE.
Main problems: weak layers, wet snow, wind slab, new snow
Danger pattern: Rain
Danger pattern: Cooling after warm weather / warming after cold

Risk assessment
Avalanche danger is CONSIDERABLE, level 3 above 1800 m, MODERATE, level 2 lower down. Especially in the high mountains of the Julian Alps, small avalanches of fresh, poorly bonded snow can release from steep slopes; with the southwesterly wind, new wind slabs have formed where a slab avalanche can be triggered with a small load. Persistent weak layers hidden in the old snow continue to pose a threat - additional loading from new precipitation and wind-transported snow will overload them in places and increase the likelihood of avalanche release. Below 1800 m, wet snow avalanches can release due to warm temperatures and rain, and on grassy or leaf-covered slopes, even gliding avalanches. Conditions are unfavourable and demanding and will deteriorate further with new precipitation, least so in the eastern Karawanks.

Snow conditions
In warm and occasionally rainy weather, the snowpack on sun-exposed slopes has been rapidly transforming and melting. Snow has wet the snowpack below around 1800 m; pronounced sun-exposed slopes are locally bare up to this elevation. Higher up, especially above 2000 m, there is already some fresh snow, expected 10 to about 30 cm, possibly a bit more in the western Julian Alps. Conditions are changing rapidly.

Forecast weather development
Today, Wednesday, it will be mostly cloudy and foggy, with some sunshine occasionally only in the far northeast. Precipitation will occur occasionally, more frequently in the Julian Alps and foothills as well as in the western and central Karawanks. Snow line between 1600 and 1900 m above sea level. Moderate wind blowing, strong southwesterly in the high mountains. Zero isotherm around 2000 m above sea level. At night, precipitation will temporarily spread across all of Slovenia, snow line will drop slightly. On Thursday, it will partly clear in many places, summits often in clouds. Mainly in the western and southern Julian Alps and hills of northern Primorska and Notranjska it will be cloudy, with occasional precipitation and snow line around 1600 m. Strong southwesterly wind. On Friday morning, precipitation will intensify and gradually spread eastwards. Snow line will rise, then fall towards evening. Only in the northern part of the Julian Alps and western and central Karawanks will the snow line remain lower, around 1200 m, rising slightly as precipitation weakens. Southerly wind strengthening in the morning, weakening and turning southwesterly in the afternoon. By Friday morning, another around 30 cm of snow above 1800 m, possibly more than 80 cm in the Western and Southern Julian Alps. Temperatures similar all days, +3 °C at 1500 m, around 0 °C at 2000 m.

Trend in snow conditions
SNOW AND AVALANCHE CONDITIONS ARE DEMANDING AND WILL CHANGE AND DETERIORATE IN THE COMING DAYS. Below about 1800 m, snow will melt due to positive temperatures and occasional rain; wet snow avalanches may release spontaneously from steep slopes, possibly even gliding avalanches. The snowpack will be saturated to the ground in places, with occasional snow. In the high mountains, especially above 2000 m a.s.l., conditions remain wintry. New snow will likely bond well to the base, less stable in fresh wind slabs built by the southwesterly. There, a small dry slab avalanche can be triggered with minimal additional load, and spontaneously from steep slopes. Persistent weak layers of faceted crystals and depth hoar will persist in the high mountains. Buried deeper in the snowpack (50-80 cm), they will be harder to overload, but any overload will result in deeper, larger avalanches. With precipitation and wind loading, these weak layers may become overloaded in many places, so spontaneous release of medium-sized and large dry slab avalanches is expected in the high mountains. Overload of deep weak layers can also be triggered by stress from a smaller shallow slab avalanche, leading to chain reactions. Such a snowpack structure is not typical for normal winters in our mountains, so we lack much experience. Essential to take measures to reduce snowpack loading when crossing, especially on steep slopes, near ridges, at gully outlets, and under walls.

Next issue: Saturday, 15. 3. 2025

Source: ARSO